Remisporine B is a polyketide, that can be isolated from Penicillium sp. ZJ-SY2. Remisporine B exhibits immunosuppressive efficacy, that inhibits concanavalin A -induced T-cell proliferation and LPS - induced B-cell proliferations of mouse splenic lymphocytes with IC 50 of 30.1 µg/mL and 32.4 µg/mL.